Gareth Morgan is compiling a national database of stray cat colonies as part of his crusade to protect native birds from feline predators.
The philanthropist economist - who offered to pay the SPCA a $5 bounty for every free-ranging, homeless cat destroyed by an authorised pound - has now asked the public to help identify all known cat colonies.
The information would bolster his calls for cats to be managed like dogs, with registration and micro-chipping, and for stray and feral cats to be euthanised.
Victoria University ecology professor Charles Daugherty backs Dr Morgan and said building a database was the first step in addressing the cat colony problem because it would provide a credible scientific research basis for programmes to reduce exploding cat populations.
Some estimates put the cat population at up to 1.5 million.
Dr Morgan has also railed against the SPCA's trap, neuter and return (TNR) policy - saying the scheme does not work.
"I want the SPCA to come to its senses," he said.
Of the SPCA's 47 branches, only Wellington, Waihi and Marlborough have active TNR programmes.
SPCA national chief executive Robyn Kippenberger said the programme was the only one proven to work but it had not been rolled out to all branches because it was expensive, costing at least $80 per neutered cat.
In October, the society would bring in British consultant Ian MacFarlane to train branches in how to effectively implement TNR, she said.
Wellington SPCA animal care and adoptions manager Nick Taylor said the TNR programme in the capital was largely focused on strays living near suburban houses and not on large cat clusters. Mr Taylor would not reveal how many colonies were in Wellington SPCA's jurisdiction or where they were.
The society "want to avoid talking about colonies" because overseas evidence suggests a media focus on the issue lead to spikes in cat dumping.
But Mr Taylor did not disagree with the principle of creating a colony database and said it would be useful in tackling the problem of escalating and unwanted cat populations.
The Wellington suburb Strathmore has up to 12 separate cat colonies, many centred around Housing New Zealand properties. Mr Taylor said two of those colonies targeted with TNR programmes had quickly reduced numbers.
Dr Morgan is holding a public meeting in Allen Ward Hall, Donald St, next Wednesday at 7pm to challenge Karori to become the first "confined cat-only" suburb. The forum will look at ways of enhancing the predator-free "halo" around wildlife sanctuary Zealandia.
- The Dominion Post